1. Field of the Invention
The present invention relates to a thin-film magnetic head having a magnetoresistance effect element for example, and shield layers thereabove and thereunder, and particularly relates to a thin-film magnetic head with superb thermal dissipation.
2. Description of the Related Art
Thin-film magnetic heads mounted in hard disk devices and the like are generally compound type thin-film magnetic heads of reproducing MR heads which exhibit giant magnetoresistve effects and recording inductive heads formed of cores and coils. With MR heads, heat is generated by a detecting current flowing through a magnetoresistance effect element, and with inductive heads, heat is generated by a recording current flowing through a coil. The heat from each of these make the interior of the thin-film magnetic head hot, causing many problems such as leading to deterioration of reproduction properties by destroying the magnetoresistance effect element, causing the portion of the inductive head to protrude farther than the other portion due to difference in thermal expansion such that the thin-film magnetic head collides with the recording medium, and so forth. Accordingly, a thin-film magnetic head structure with superb thermal dissipation to lower the internal temperature of the thin-film magnetic head is in urgent need.
Examples of conventional art with improvement of thermal dissipation effects as the object thereof include Japanese Unexamined Patent Application Publication No. 2002-216314 and Japanese Unexamined Patent Application Publication No. 2001-236614.
With the arrangement disclosed in Japanese Unexamined Patent Application Publication No. 2002-216314, a first shield layer 31 provided below a MR element 9 is formed very long in the height direction from the face facing a recording medium, with hope that the portion of the first shield layer 31 extending in the height direction for a long distance (e.g., the portion thereof extending hindwards in the height direction beyond a hind connecting portion 42) will provide thermal dissipation effects.
However, in this arrangement, the first shield layer 31 is formed on a smoothed inorganic insulating film 710 formed on a slider 73, so the first shield layer 31 and the slider 73 are separated by the a distance equal to the thickness of the inorganic insulating film 710. The inorganic insulating film 710 is formed of Al2O3 or the like for example, but the thermal conductivity of Al2O3 is lower than that of metal film, so there is the problem that the heat transmitted to the first shield layer 31 cannot be efficiently discharged to the slider 73. As a result, the heat remains within the thin-film magnetic head, making the inside of the thin-film magnetic head hot, and accordingly cannot effectively solve the above-described problems of reproduction properties and head damage.
Also, forming the first shield layer 31 extended very long in the height direction to increase the area of the first shield layer 31 also causes the problem that the electron beam in the exposure step for forming the MR element 9 on the first shield layer 31 is bent due to the floating magnetic field emitted from the first shield layer 31, so the MR element 9 cannot be formed in the predetermined shape with high precision.
The arrangement disclosed in Japanese Unexamined Patent Application Publication No. 2001-236614 similarly has a lower magnetic shield 21 and a copper heat-radiating fin 26 behind this formed on a smoothed surface of an insulating layer 12 formed on a substrate 1. Accordingly, the distance between the lower magnetic shield 21 and copper heat-radiating fin 26, and the substrate 1 is widened, so heat transmitted to the lower magnetic shield 21 and copper heat-radiating fin 26 is not efficiently discharged to the substrate 1.
Also, forming the first shield layer 31 so as to be extended long in the height direction as with Patent Document 1, or forming the lower magnetic shield 21 and the copper heat-radiating fin 26 in contact as with Patent Document 2, may cause a part of the heat absorbed by the first shield layer 31 and copper heat radiating fin 26 to be transmitted to the side facing the recording medium, which may destroy the MR element.
Also, with the arrangement disclosed in Japanese Unexamined Patent Application Publication No. 2002-216314, the second shield film is formed extended long in the height direction in the same way as with the first shield film, but the entire second shield film is on an insulating layer covering the MR element, so the distance between the second shield film and the slider is even greater than that between the first shield film and the slider, so heat cannot be effectively discharged directly from the second shield film to the slider. Accordingly, the heat absorbed by the second shield film passes through the first shield film and is indirectly discharged to the slider, but indirect discharge does not allow the heat absorbed by the second shield film to be more effectively transmitted, so there is the possibility that the heat may still remain within the second shield film.
Also, an electrode extracting layer for supplying detecting current to the magnetoresistance effect element is connected to the magnetoresistance effect element, so the position for forming the electrode extracting layer needs to be taken into consideration in order to effectively reduce the distance between the second shield film and the slider, but this electrode extracting layer is neither disclosed nor even suggested in Japanese Unexamined Patent Application Publication No. 2002-216314, and the above-described problem is similarly unsolved by the art disclosed in Japanese Unexamined Patent Application Publication No. 2001-236614.